In order to sync the Wiki with the main code to generate the GitHub pages, it is necessary to have the main code cloned:
git clone https://github.com/angoca/db2-index.git
cd db2-index
Then, add a remote branch to point to the wiki.
git remote add angoca git://github.com/angoca/db2-index.wiki.git
And finally, pull changes and integrate them into the other:
git pull angoca master --allow-unrelated-histories
git pull
git push